//
   //  ========================================================================
   //  Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.annotations;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.URI;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Locale;
  import java.util.Set;
  import java.util.concurrent.TimeUnit;
  import java.util.jar.JarEntry;
  import java.util.jar.JarFile;
  import java.util.jar.JarInputStream;
  
  import org.eclipse.jetty.util.ConcurrentHashSet;
  import org.eclipse.jetty.util.Loader;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.resource.Resource;
  import org.eclipse.jetty.webapp.JarScanner;
  import org.objectweb.asm.AnnotationVisitor;
  import org.objectweb.asm.ClassReader;
  import org.objectweb.asm.ClassVisitor;
  import org.objectweb.asm.FieldVisitor;
  import org.objectweb.asm.MethodVisitor;
  import org.objectweb.asm.Opcodes;
  
  
  /**
   * AnnotationParser
   *
   * Use asm to scan classes for annotations. A SAX-style parsing is done.
   * Handlers are registered which will be called back when various types of
   * entity are encountered, eg a class, a method, a field. 
   * 
   * Handlers are not called back in any particular order and are assumed
   * to be order-independent.
   * 
   * As a registered Handler will be called back for each annotation discovered
   * on a class, a method, a field, the Handler should test to see if the annotation
   * is one that it is interested in.
   * 
   * For the servlet spec, we are only interested in annotations on classes, methods and fields,
   * so the callbacks for handling finding a class, a method a field are themselves
   * not fully implemented.
   */
  public class AnnotationParser
  {
      private static final Logger LOG = Log.getLogger(AnnotationParser.class);
  
      protected Set<String> _parsedClassNames = new ConcurrentHashSet<String>();
     
  
      /**
       * Convert internal name to simple name
       * 
       * @param name
       * @return
       */
      public static String normalize (String name)
      {
          if (name==null)
              return null;
  
          if (name.startsWith("L") && name.endsWith(";"))
              name = name.substring(1, name.length()-1);
  
          if (name.endsWith(".class"))
              name = name.substring(0, name.length()-".class".length());
  
          return name.replace('/', '.');
      }
      
      /**
      * Convert internal names to simple names.
      * 
      * @param list
      * @return
      */
     public static String[] normalize (String[] list)
     {
         if (list == null)
             return null;       
         String[] normalList = new String[list.length];
         int i=0;
         for (String s : list)
             normalList[i++] = normalize(s);
         return normalList;
     }
 
     
     /**
      * ClassInfo
      * 
      * Immutable information gathered by parsing class header.
      * 
      */
     public class ClassInfo 
     {
         final Resource _containingResource;
         final String _className;
         final int _version;
         final int _access;
         final String _signature;
         final String _superName; 
         final String[] _interfaces;
         
         public ClassInfo(Resource resource, String className, int version, int access, String signature, String superName, String[] interfaces)
         {
             super();
             _containingResource = resource;
             _className = className;
             _version = version;
             _access = access;
             _signature = signature;
             _superName = superName;
             _interfaces = interfaces;
         }
 
         public String getClassName()
         {
             return _className;
         }
 
         public int getVersion()
         {
             return _version;
         }
 
         public int getAccess()
         {
             return _access;
         }
 
         public String getSignature()
         {
             return _signature;
         }
 
         public String getSuperName()
         {
             return _superName;
         }
 
         public String[] getInterfaces()
         {
             return _interfaces;
         }
 
         public Resource getContainingResource()
         {
             return _containingResource;
         }
     }
 
     
     /**
      * MethodInfo
      * 
      * Immutable information gathered by parsing a method on a class.
      */
     public class MethodInfo
     {
         final ClassInfo _classInfo;
         final String _methodName; 
         final int _access;
         final String _desc; 
         final String _signature;
         final String[] _exceptions;
         
         public MethodInfo(ClassInfo classInfo, String methodName, int access, String desc, String signature, String[] exceptions)
         {
             super();
             _classInfo = classInfo;
             _methodName = methodName;
             _access = access;
             _desc = desc;
             _signature = signature;
             _exceptions = exceptions;
         }
 
         public ClassInfo getClassInfo()
         {
             return _classInfo;
         }
 
         public String getMethodName()
         {
             return _methodName;
         }
 
         public int getAccess()
         {
             return _access;
         }
 
         public String getDesc()
         {
             return _desc;
         }
 
         public String getSignature()
         {
             return _signature;
         }
 
         public String[] getExceptions()
         {
             return _exceptions;
         }
     }
     
     
     
     /**
      * FieldInfo
      *
      * Immutable information gathered by parsing a field on a class.
      * 
      */
     public class FieldInfo
     {
         final ClassInfo _classInfo;
         final String _fieldName;
         final int _access;
         final String _fieldType;
         final String _signature;
         final Object _value;
         
         public FieldInfo(ClassInfo classInfo, String fieldName, int access, String fieldType, String signature, Object value)
         {
             super();
             _classInfo = classInfo;
             _fieldName = fieldName;
             _access = access;
             _fieldType = fieldType;
             _signature = signature;
             _value = value;
         }
 
         public ClassInfo getClassInfo()
         {
             return _classInfo;
         }
 
         public String getFieldName()
         {
             return _fieldName;
         }
 
         public int getAccess()
         {
             return _access;
         }
 
         public String getFieldType()
         {
             return _fieldType;
         }
 
         public String getSignature()
         {
             return _signature;
         }
 
         public Object getValue()
         {
             return _value;
         }
     }
     
     
     /**
      * Handler
      *
      * Signature for all handlers that respond to parsing class files.
      */
     public static interface Handler
     {
         public void handle(ClassInfo classInfo);
         public void handle(MethodInfo methodInfo);
         public void handle (FieldInfo fieldInfo);
         public void handle (ClassInfo info, String annotationName);
         public void handle (MethodInfo info, String annotationName);
         public void handle (FieldInfo info, String annotationName);
     }
     
     
     
     /**
      * AbstractHandler
      *
      * Convenience base class to provide no-ops for all Handler methods.
      * 
      */
     public static abstract class AbstractHandler implements Handler
     {
 
         @Override
         public void handle(ClassInfo classInfo)
         {
            //no-op
         }
 
         @Override
         public void handle(MethodInfo methodInfo)
         {
             // no-op           
         }
 
         @Override
         public void handle(FieldInfo fieldInfo)
         {
             // no-op 
         }
 
         @Override
         public void handle(ClassInfo info, String annotationName)
         {
             // no-op 
         }
 
         @Override
         public void handle(MethodInfo info, String annotationName)
         {
             // no-op            
         }
 
         @Override
         public void handle(FieldInfo info, String annotationName)
         {
            // no-op
         }        
     }
 
     
     
     /**
      * MyMethodVisitor
      * 
      * ASM Visitor for parsing a method. We are only interested in the annotations on methods.
      */
     public class MyMethodVisitor extends MethodVisitor
     {
         final MethodInfo _mi;
         final Set<? extends Handler> _handlers;
         
             
         /**
          * @param classname
          * @param access
          * @param name
          * @param methodDesc
          * @param signature
          * @param exceptions
          */
         public MyMethodVisitor(final Set<? extends Handler> handlers,
                                final ClassInfo classInfo,
                                final int access,
                                final String name,
                                final String methodDesc,
                                final String signature,
                                final String[] exceptions)
         {
             super(Opcodes.ASM4);
             _handlers = handlers;
             _mi = new MethodInfo(classInfo, name, access, methodDesc,signature, exceptions);
         }
 
         
         /**
          * We are only interested in finding the annotations on methods.
          * 
          * @see org.objectweb.asm.MethodVisitor#visitAnnotation(java.lang.String, boolean)
          */
         @Override
         public AnnotationVisitor visitAnnotation(String desc, boolean visible)
         {
             String annotationName = normalize(desc);
             for (Handler h:_handlers)
                 h.handle(_mi, annotationName);
             return null;
         }
     }
 
 
     
     /**
      * MyFieldVisitor
      * 
      * An ASM visitor for parsing Fields. 
      * We are only interested in visiting annotations on Fields.
      *
      */
     public class MyFieldVisitor extends FieldVisitor
     {   
         final FieldInfo _fieldInfo;
         final Set<? extends Handler> _handlers;
         
     
         /**
          * @param classname
          */
         public MyFieldVisitor(final Set<? extends Handler> handlers,
                               final ClassInfo classInfo,
                               final int access,
                               final String fieldName,
                               final String fieldType,
                               final String signature,
                               final Object value)
         {
             super(Opcodes.ASM4);
             _handlers = handlers;
             _fieldInfo = new FieldInfo(classInfo, fieldName, access, fieldType, signature, value);
         }
 
 
         /**
          * Parse an annotation found on a Field.
          * 
          * @see org.objectweb.asm.FieldVisitor#visitAnnotation(java.lang.String, boolean)
          */
         @Override
         public AnnotationVisitor visitAnnotation(String desc, boolean visible)
         {
             String annotationName = normalize(desc);
             for (Handler h : _handlers)
                h.handle(_fieldInfo, annotationName);
 
             return null;
         }
     }
 
   
 
 
     /**
      * MyClassVisitor
      *
      * ASM visitor for a class.
      */
     public class MyClassVisitor extends ClassVisitor
     {
 
         final Resource _containingResource;
         final Set<? extends Handler> _handlers;
         ClassInfo _ci;
         
         public MyClassVisitor(Set<? extends Handler> handlers, Resource containingResource)
         {
             super(Opcodes.ASM4);
             _handlers = handlers;
             _containingResource = containingResource;
         }
 
 
         @Override
         public void visit (final int version,
                            final int access,
                            final String name,
                            final String signature,
                            final String superName,
                            final String[] interfaces)
         {           
             _ci = new ClassInfo(_containingResource, normalize(name), version, access, signature, normalize(superName), normalize(interfaces));
             
             _parsedClassNames.add(_ci.getClassName());                 
 
             for (Handler h:_handlers)
                h.handle(_ci);
         }
         
 
         /**
          * Visit an annotation on a Class
          * 
          * @see org.objectweb.asm.ClassVisitor#visitAnnotation(java.lang.String, boolean)
          */
         @Override
         public AnnotationVisitor visitAnnotation (String desc, boolean visible)
         {
             String annotationName = normalize(desc);
             for (Handler h : _handlers)
                 h.handle(_ci, annotationName);
 
             return null;
         }
 
 
         /**
          * Visit a method to extract its annotations
          * 
          * @see org.objectweb.asm.ClassVisitor#visitMethod(int, java.lang.String, java.lang.String, java.lang.String, java.lang.String[])
          */
         @Override
         public MethodVisitor visitMethod (final int access,
                                           final String name,
                                           final String methodDesc,
                                           final String signature,
                                           final String[] exceptions)
         {
 
             return new MyMethodVisitor(_handlers, _ci, access, name, methodDesc, signature, exceptions);
         }
 
         /**
          * Visit a field to extract its annotations
          * 
          * @see org.objectweb.asm.ClassVisitor#visitField(int, java.lang.String, java.lang.String, java.lang.String, java.lang.Object)
          */
         @Override
         public FieldVisitor visitField (final int access,
                                         final String fieldName,
                                         final String fieldType,
                                         final String signature,
                                         final Object value)
         {
             return new MyFieldVisitor(_handlers, _ci, access, fieldName, fieldType, signature, value);
         }
     }
 
  
 
     /**
      * True if the class has already been processed, false otherwise
      * @param className
      */
     public boolean isParsed (String className)
     {
         return _parsedClassNames.contains(className);
     }
 
     
     
     /**
      * Parse a given class
      * 
      * @param className
      * @param resolver
      * @throws Exception
      */
     public void parse (Set<? extends Handler> handlers, String className, ClassNameResolver resolver)
     throws Exception
     {
         if (className == null)
             return;
 
         if (!resolver.isExcluded(className))
         {
             if (!isParsed(className) || resolver.shouldOverride(className))
             {
                 className = className.replace('.', '/')+".class";
                 URL resource = Loader.getResource(this.getClass(), className);
                 if (resource!= null)
                 {
                     Resource r = Resource.newResource(resource);
                     scanClass(handlers, null, r.getInputStream());
                 }
             }
         }
     }
 
     
     
     /**
      * Parse the given class, optionally walking its inheritance hierarchy
      * 
      * @param clazz
      * @param resolver
      * @param visitSuperClasses
      * @throws Exception
      */
     public void parse (Set<? extends Handler> handlers, Class<?> clazz, ClassNameResolver resolver, boolean visitSuperClasses)
     throws Exception
     {
         Class<?> cz = clazz;
         while (cz != null)
         {
             if (!resolver.isExcluded(cz.getName()))
             {
                 if (!isParsed(cz.getName()) || resolver.shouldOverride(cz.getName()))
                 {
                     String nameAsResource = cz.getName().replace('.', '/')+".class";
                     URL resource = Loader.getResource(this.getClass(), nameAsResource);
                     if (resource!= null)
                     {
                         Resource r = Resource.newResource(resource);
                         scanClass(handlers, null, r.getInputStream());
                     }
                 }
             }
             if (visitSuperClasses)
                 cz = cz.getSuperclass();
             else
                 cz = null;
         }
     }
 
     
     
     /**
      * Parse the given classes
      * 
      * @param classNames
      * @param resolver
      * @throws Exception
      */
     public void parse (Set<? extends Handler> handlers, String[] classNames, ClassNameResolver resolver)
     throws Exception
     {
         if (classNames == null)
             return;
 
         parse(handlers, Arrays.asList(classNames), resolver);
     }
 
     
     /**
      * Parse the given classes
      * 
      * @param classNames
      * @param resolver
      * @throws Exception
      */
     public void parse (Set<? extends Handler> handlers, List<String> classNames, ClassNameResolver resolver)
     throws Exception
     {
         for (String s:classNames)
         {
             if ((resolver == null) || (!resolver.isExcluded(s) &&  (!isParsed(s) || resolver.shouldOverride(s))))
             {
                 s = s.replace('.', '/')+".class";
                 URL resource = Loader.getResource(this.getClass(), s);
                 if (resource!= null)
                 {
                     Resource r = Resource.newResource(resource);
                     scanClass(handlers, null, r.getInputStream());
                 }
             }
         }
     }
 
     
     /**
      * Parse all classes in a directory
      * 
      * @param dir
      * @param resolver
      * @throws Exception
      */
     protected void parseDir (Set<? extends Handler> handlers, Resource dir, ClassNameResolver resolver)
     throws Exception
     {
         //skip dirs whose name start with . (ie hidden)
         if (!dir.isDirectory() || !dir.exists() || dir.getName().startsWith("."))
             return;
 
         if (LOG.isDebugEnabled()) {LOG.debug("Scanning dir {}", dir);};
 
         String[] files=dir.list();
         for (int f=0;files!=null && f<files.length;f++)
         {
             try
             {
                 Resource res = dir.addPath(files[f]);
                 if (res.isDirectory())
                     parseDir(handlers, res, resolver);
                 else
                 {
                     //we've already verified the directories, so just verify the class file name
                     boolean valid = true;
                     File file = res.getFile();
                     if (file == null)
                         LOG.warn("Unable to validate class file name for {}", res);
                     else
                         valid = isValidClassFileName(file.getName());
                    
                     if (valid)
                     {
                         String name = res.getName();
                         if ((resolver == null)|| (!resolver.isExcluded(name) && (!isParsed(name) || resolver.shouldOverride(name))))
                         {
                             Resource r = Resource.newResource(res.getURL());
                             if (LOG.isDebugEnabled()) {LOG.debug("Scanning class {}", r);};
                             scanClass(handlers, dir, r.getInputStream());
                         }
 
                     }
                 }
             }
             catch (Exception ex)
             {
                 LOG.warn(Log.EXCEPTION,ex);
             }
         }
     }
 
 
     /**
      * Parse classes in the supplied classloader. 
      * Only class files in jar files will be scanned.
      * 
      * @param loader
      * @param visitParents
      * @param nullInclusive
      * @param resolver
      * @throws Exception
      */
     public void parse (final Set<? extends Handler> handlers, ClassLoader loader, boolean visitParents, boolean nullInclusive, final ClassNameResolver resolver)
     throws Exception
     {
         if (loader==null)
             return;
 
         if (!(loader instanceof URLClassLoader))
             return; //can't extract classes?
 
         JarScanner scanner = new JarScanner()
         {
             @Override
             public void processEntry(URI jarUri, JarEntry entry)
             {
                 try
                 {
                     parseJarEntry(handlers, Resource.newResource(jarUri), entry, resolver);
                 }
                 catch (Exception e)
                 {
                     LOG.warn("Problem parsing jar entry: {}", entry.getName());
                 }
             }
 
         };
 
         scanner.scan(null, loader, nullInclusive, visitParents);
     }
 
 
     /**
      * Parse classes in the supplied uris.
      * 
      * @param uris
      * @param resolver
      * @throws Exception
      */
     public void parse (final Set<? extends Handler> handlers, final URI[] uris, final ClassNameResolver resolver)
     throws Exception
     {
         if (uris==null)
             return;
 
         for (URI uri:uris)
         {
             try
             {
                 parse(handlers, uri, resolver);
             }
             catch (Exception e)
             {
                 LOG.warn("Problem parsing classes from {}", uri);
             }
         }
 
     }
 
     /**
      * Parse a particular uri
      * @param uri
      * @param resolver
      * @throws Exception
      */
     public void parse (final Set<? extends Handler> handlers, URI uri, final ClassNameResolver resolver)
     throws Exception
     {
         if (uri == null)
             return;
 
         parse (handlers, Resource.newResource(uri), resolver);
         
      
     }
 
     
     /**
      * Parse a resource
      * @param r
      * @param resolver
      * @throws Exception
      */
     public void parse (final Set<? extends Handler> handlers, Resource r, final ClassNameResolver resolver)
     throws Exception
     {
         if (r == null)
             return;
         
         if (r.exists() && r.isDirectory())
         {
             parseDir(handlers, r, resolver);
             return;
         }
 
         String fullname = r.toString();
         if (fullname.endsWith(".jar"))
         {
             parseJar(handlers, r, resolver);
             return;
         }
 
         if (fullname.endsWith(".class"))
         {
             scanClass(handlers, null, r.getInputStream());
             return;
         }
         
         if (LOG.isDebugEnabled()) LOG.warn("Resource not scannable for classes: {}", r);
     }
 
     
   
 
     /**
      * Parse a resource that is a jar file.
      * 
      * @param jarResource
      * @param resolver
      * @throws Exception
      */
     protected void parseJar (Set<? extends Handler> handlers, Resource jarResource,  final ClassNameResolver resolver)
     throws Exception
     {
         if (jarResource == null)
             return;
        
         if (jarResource.toString().endsWith(".jar"))
         {
             if (LOG.isDebugEnabled()) {LOG.debug("Scanning jar {}", jarResource);};
 
             //treat it as a jar that we need to open and scan all entries from  
             //TODO alternative impl
             /*
             long start = System.nanoTime();
             Collection<Resource> resources = Resource.newResource("jar:"+jarResource+"!/").getAllResources();
             System.err.println(jarResource+String.valueOf(resources.size())+" resources listed in "+ ((TimeUnit.MILLISECONDS.convert(System.nanoTime()-start, TimeUnit.NANOSECONDS))));
             for (Resource r:resources)
             {
                 //skip directories
                 if (r.isDirectory())
                     continue;
 
                 String name = r.getName();
                 name = name.substring(name.indexOf("!/")+2);
 
                 //check file is a valid class file name
                 if (isValidClassFileName(name) && isValidClassFilePath(name))
                 {
                     String shortName =  name.replace('/', '.').substring(0,name.length()-6);
 
                     if ((resolver == null)
                             ||
                         (!resolver.isExcluded(shortName) && (!isParsed(shortName) || resolver.shouldOverride(shortName))))
                     {
                         if (LOG.isDebugEnabled()) {LOG.debug("Scanning class from jar {}", r);};
                         scanClass(handlers, jarResource, r.getInputStream());
                     }
                 }
             }
             */
 
            InputStream in = jarResource.getInputStream();
             if (in==null)
                 return;
 
             JarInputStream jar_in = new JarInputStream(in);
             try
             { 
                 JarEntry entry = jar_in.getNextJarEntry();
                 while (entry!=null)
                 {      
                     parseJarEntry(handlers, jarResource, entry, resolver);
                     entry = jar_in.getNextJarEntry();
                 }
             }
             finally
             {
                 jar_in.close();
             }
         }   
     }
 
     /**
      * Parse a single entry in a jar file
      * @param jar
      * @param entry
      * @param resolver
      * @throws Exception
      */
     protected void parseJarEntry (Set<? extends Handler> handlers, Resource jar, JarEntry entry, final ClassNameResolver resolver)
     throws Exception
     {
         if (jar == null || entry == null)
             return;
 
         //skip directories
         if (entry.isDirectory())
             return;
 
         String name = entry.getName();
 
         //check file is a valid class file name
         if (isValidClassFileName(name) && isValidClassFilePath(name))
         {
             String shortName =  name.replace('/', '.').substring(0,name.length()-6);
 
             if ((resolver == null)
                     ||
                 (!resolver.isExcluded(shortName) && (!isParsed(shortName) || resolver.shouldOverride(shortName))))
             {
                 Resource clazz = Resource.newResource("jar:"+jar.getURI()+"!/"+name);
                 if (LOG.isDebugEnabled()) {LOG.debug("Scanning class from jar {}", clazz);};
                 scanClass(handlers, jar, clazz.getInputStream());
             }
         }
     }
     
     
 
     /**
      * Use ASM on a class
      * 
      * @param containingResource the dir or jar that the class is contained within, can be null if not known
      * @param is
      * @throws IOException
      */
     protected void scanClass (Set<? extends Handler> handlers, Resource containingResource, InputStream is)
     throws IOException
     {
         ClassReader reader = new ClassReader(is);
         reader.accept(new MyClassVisitor(handlers, containingResource), ClassReader.SKIP_CODE|ClassReader.SKIP_DEBUG|ClassReader.SKIP_FRAMES);
     }
     
     /**
      * Check that the given path represents a valid class file name.
      * The check is fairly cursory, checking that:
      * <ul>
      * <li> the name ends with .class</li>
      * <li> it isn't a dot file or in a hidden directory </li>
      * <li> the name of the class at least begins with a valid identifier for a class name </li>
      * </ul>
      * @param name
      * @return
      */
     private boolean isValidClassFileName (String name)
     {
         //no name cannot be valid
         if (name == null || name.length()==0)
             return false;
 
         //skip anything that is not a class file
         if (!name.toLowerCase(Locale.ENGLISH).endsWith(".class"))
         {
             if (LOG.isDebugEnabled()) LOG.debug("Not a class: {}",name);
             return false;
         }
 
         //skip any classfiles that are not a valid java identifier
         int c0 = 0;      
         int ldir = name.lastIndexOf('/', name.length()-6);
         c0 = (ldir > -1 ? ldir+1 : c0);
         if (!Character.isJavaIdentifierStart(name.charAt(c0)))
         {
             if (LOG.isDebugEnabled()) LOG.debug("Not a java identifier: {}"+name);
             return false;
         }
    
         return true;
     }
     
     
     /**
      * Check that the given path does not contain hidden directories
      *
      * @param path
      * @return
      */
     private boolean isValidClassFilePath (String path)
     {
         //no path is not valid
         if (path == null || path.length()==0)
             return false;
 
         //skip any classfiles that are in a hidden directory
         if (path.startsWith(".") || path.contains("/."))
         {
             if (LOG.isDebugEnabled()) LOG.debug("Contains hidden dirs: {}"+path);
             return false;
         }
 
         return true;
     }
 }